US intelligence agents questioned the value of a Libyan double agent in Malta who now is a key witness at the Lockerbie bombing trial, reported AFP, quoting defense lawyers on Tuesday.

Speaking at the trial of two Libyans accused of the 1988 downing of Pan Am Flight 103, the lawyers said US handlers of Abdul Majid Giaka suspected that his main concern was to avoid military service in Libya, said the AFP.

They cited cables from CIA agents in Malta to the agency's headquarters outside Washington, one of which was dated September 1st 1989, almost nine months after the Lockerbie bombing.

"It is clear that P1 will never have the penetration of Libyan intelligence service that we had anticipated," the cable said, using Gaika's code-name within the US Central Intelligence Agency.

"P1 has never been a true member of Libyan intelligence," the cable continued. "We'll advise P1 that he is on trial status until 1st January 1990."

The CIA operative who wrote the cable also suggested that the agency cut off Gaika's salary of 1,000 dollars per month if he supplied no significant information, said the agency.

"He was proving to be of very little value to the Americans," defense lawyer William Taylor told the court, arguing that the cables showed Gaika was unreliable and of little use to US intelligence gatherers.

Gaika, 40, has yet to testify against Abdel Basset Ali al-Megrahi and Al-Amin Khalifa Fhimah, charged with blowing up Pan American Flight 103 over the Scottish town of Lockerbie on December 21st, 1988, killing 270 people.

The two Libyans, also alleged to have been Libyan secret agents, have pleaded not guilty to the charges, added AFP.

The trial opened on May 3rd and is expected to wind up by Christmas, said the agency.

Gaika was scheduled to testify last week before defense lawyers demanded equal access to unexpurgated versions of the CIA cables which US officials showed to two prosecuting lawyers in June, reported the BBC.online Monday.

Observers expected Gaika to claim in the witness box that he saw Megrahi and Fhimah in Malta where they allegedly put a suitcase containing a bomb onto a flight to Frankfurt, tagged for transfer to London and Pan Am Flight 103, said the BBC.

Gaika, who has been living for a decade under the US witness protection program, is understood to be already at Camp Zeist, where security has been stepped up noticeably in the last few days, the BBC added.

Gaika is due to be called to give evidence this week, said the BBC - (Several Sources)